Class 12th

The peak electric field produced by the radiation coming from the 8W bulb at a distance of 10m is $\frac{x}{10}\sqrt[]{\frac{{\mu }_{0}c}{\pi }}\frac{V}{m}.$ The efficiency of the bulb is 10% and it is a point source. The value of x is…….

Two identical conducting spheres with negligible volume have 2.1 nC and 0.1 nC charges, respectively. They are brought into contact and then separated by a distance of 0.5m. The electrostatic force acting between the spheres is …………….* 10^-9N.

$\left[Given:4\pi {\epsilon }_0=\frac{1}{9*10^9}SIunit\right]$

The wavelength of an X-ray beam is $10\stackrel{o}{A}.$ The mass of a fictitious particle having the same energy as that of the X-ray photons is $\frac{x}{3}hkg.$ The value of x is………. (h = Planck's constant)

A current of 6 A enters one corner P of an equilateral triangle PQR having 3 wires of resistance $2\Omega$  each and leaves by the corner R. The currents i₁ in ampere is………

Two small spheres each of mass 10mg are suspended from a point by threads 0.5m long. They are equally charged and repel each other to a distance of 0.20m. The charge on each of the sphere is $\frac{a}{21}*10^{-8}C.$  The value of 'a' will be……. [Given g = 10 ms^-2]

An electron with kinetic energy K₁ enters between parallel plates of a capacitor at an angle 'α' with the plates. It leaves the plates at angle 'β' with kinetic energy K₂. Then the ratio of kinetic energies K₁ : K₂ will be

In a ferromagnetic region with zero magnetization.

The wavelength of the photon emitted by a hydrogen atom when an electron makes a transition from n = 2 to n = 1 state is

An electron of mass m_e and a proton of mass m_p = 1836 m_e are moving with the same speed. The ratio of their de Broglie wavelength $\frac{{\lambda }_{electron}}{{\lambda }_{proton}}$  will be